Resin composition, molded product thereof and electroconductive sheet

ABSTRACT

An electroconductive sheet comprising a substrate layer of a thermoplastic resin comprising an acrylonitrile-butadiene-styrene copolymer type resin and/or a polystyrene type resin and having laminated on at least one side of the substrate layer, a surface layer of an electroconductive resin composition comprising a polycarbonate type resin and from 5 to 50 wt % of carbon black.

TECHNICAL FIELD

[0001] The present invention relates to a resin composition, a moldedproduct employing it and an electroconductive sheet. Saidelectroconductive sheet is useful for packaging containers forsemiconductors such as IC and electronic parts, particularly useful forcarrier tapes.

BACKGROUND ART

[0002] For packaging IC, electronic parts using IC or electronic parts,injection-molded trays, vacuum-formed trays, magazines, carrier tapes(referred to also as embossed carrier tapes) etc. have been used. Toprevent breakage of electronic parts such as IC due to staticelectricity, as the packaging containers, ones having anelectroconductive filler dispersed therein have been used. As theelectroconductive filler, carbon black is widely used, with which astable surface resistivity will be obtained constantly at a low cost.

[0003] An electroconductive sheet comprising a thermoplastic resinhaving carbon black dispersed therein, has such drawbacks that (1)mechanical strength and processability will decrease, and (2) anelectronic part will be stained by falling off of the resin containingcarbon black on the surface of the electroconductive sheet by abrasionof the packaged electronic part with the electroconductive sheet.JP-A-57-205145, JP-A-62-18261, etc. have been proposed as a method toovercome the problem (1), and JP-A-9-7624, JP-A-9-76425, etc. have beenproposed as a method to overcome the problem (2). However, electronicparts are getting more complex, precise and small, and packaging andmounting of electronic parts proceed at a higher speed at the presenttime, and accordingly, an electroconductive sheet for packaging anelectronic part, which is less likely to cause staining of theelectronic part, and which has improved mechanical strength, has beendesired.

DISCLOSURE OF THE INVENTION

[0004] The present invention provides an electroconductive sheet forpackaging an electronic part, which substantially reduces staining ofthe electronic part due to abrasion of the electroconductive sheet withthe electronic part, and which has adequate mechanical strength toendure packaging or mounting at a high speed, and a packaging containerfor an electronic part. The electroconductive sheet is particularlyuseful for a carrier tape.

[0005] The present invention provides an electroconductive sheetcomprising a substrate layer and having laminated on at least one sideof the substrate layer, a surface layer of an electroconductive resincomposition comprising a polycarbonate type resin and from 5 to 50 wt %of carbon black based on the polycarbonate type resin. Saidelectroconductive sheet is useful as an electroconductive sheet forpackaging an electronic part, and said electroconductive sheet forpackaging an electronic part is useful as a packaging container for anelectronic part, particularly as a carrier tape.

[0006] As a constitution of the electroconductive sheet, a two-layerstructure of surface layer/substrate layer, wherein the surface layercomprises an electroconductive resin composition and is placed on theside which will be in contact with the electronic part, is preferred.Further, a constitution of surface layer/substrate layer/surface layeris also preferred. Another layer may be provided between the surfacelayer and the substrate layer.

[0007] The polycarbonate type resin for the electroconductive resincomposition is not particularly limited, and an commercially availableproduct may be used. For example, an aromatic polycarbonate resin, analiphatic polycarbonate resin and an aromatic-aliphatic polycarbonatemay be mentioned. One obtained by polycondensation of a conventionalbisphenol A with phosgene or by polycondensation of bisphenol A withcarbonic acid ester, which is usually classified into an engineeringplastic, may also be used. This is composed mainly of bisphenol, andproduced by a phosgene method or by ester exchange, and the bisphenol tobe used as the raw material may, for example, be2,2-bis-(4-hydroxyphenyl)propane (bisphenol A),2,4-bis-(4-hydroxyphenyl)-methyl-butane or1,1-bis-(4-hydroxyphenyl)-cyclohexane. A homopolycarbonate, acopolycarbonate obtained by copolymerization of a carboxylic acid, or amixture thereof, may also be used.

[0008] Carbon black to be incorporated in the electroconductive resincomposition may, for example, be furnace black, channel black oracetylene black, and preferred is one having a large specific surfacearea and whereby a high level of electroconductivity can be obtainedwith a small amount of incorporation to the resin, such as KETJENBLACKor acetylene black.

[0009] The amount of carbon black to be incorporated in theelectroconductive resin composition is preferably from 5 to 50 wt %based on the polycarbonate type resin. If it is less than 5 wt %, noadequate surface resistivity will be obtained to prevent breakage of anelectronic part due to static electricity. If it exceeds 50 wt %, thefluidity will decrease, whereby it may be difficult to laminate theelectroconductive resin composition on the substrate layer, and themechanical strength of the electroconductive sheet to be obtained willalso decrease.

[0010] The surface resistivity of the electroconductive sheet on theside on which the electroconductive resin composition is laminated, ispreferably from 10² to 10¹⁰ Ω. If it is beyond this range, it tends tobe difficult to prevent breakage of an electronic part due to staticelectricity.

[0011] Into the electroconductive resin composition, another resincomponent such as an acrylonitrile-butadiene-styrene copolymer typeresin or a polybutylene terephthalate resin may be incorporated as amodifier.

[0012] As the modifier, a graft resin of anethylene-glycidylmethacrylate type copolymer with anacrylonitrile-styrene type copolymer is suitably used. Theelectroconductive resin composition in this case comprises apolycarbonate type resin, and from 5 to 50 wt % of carbon black and atmost 40 wt % of a graft resin of an ethylene-glycidylmethacrylate typecopolymer with an acrylonitrile-styrene type copolymer, based on thepolycarbonate type resin. The electroconductive resin composition may bemade of a polycarbonate type resin, carbon black and a graft resinalone, or may be composed mainly of those and contain another componentwithin a range of not impairing the purpose of the present invention.

[0013] The graft resin of an ethylene-glycidylmethacrylate typecopolymer with an acrylonitrile-styrene type copolymer is a resinobtained by grafting an acrylonitrile-styrene type copolymer to anethylene-glycidylmethacrylate type copolymer, and a resin obtained bygrafting an acrylonitrile-styrene type copolymer having an acrylonitrilecontent of at most 50 wt % to an ethylene-glycidylmethacrylate typecopolymer having a glycidylmethacrylate content of at most 45 wt %, issuitably used, which is commercially available.

[0014] The amount of the graft resin to be incorporated is at most 40 wt%, preferably from 1 to 40 wt %, more preferably from 3 to 40 wt %,based on the polycarbonate type resin. Within the above range, themechanical strength, particularly impact strength, will be improved toendure packaging and mounting of electronic parts at a high speed. If itexceeds 40 wt %, the elastic modulus will decrease.

[0015] When the above resin composition is used for an electroconductivesheet as an electroconductive resin composition, it may be used as amonolayer electroconductive sheet or a multilayer electroconductivesheet. It may be used as a molded product by itself.

[0016] Into the electroconductive resin composition, an additive such asa lubricant, a plasticizer or a processing aid may further beincorporated as the case requires.

[0017] The electroconductive sheet is particularly useful as a carriertape. For such an application, an electroconductive sheet for a carriertape, which has a reduced reflection on the surface, has been desired soas to prevent malfunction of an inspection machine due to reflection onthe surface of the electroconductive sheet at the time of imageinspection of e.g. IC. According to the present invention, the layer ofan electroconductive resin composition has a surface roughness Ra offrom 0.6 μm to 4.0 μm, whereby malfunction of an inspection machine dueto reflection on the electroconductive sheet surface can be prevented atthe image inspection of electronic parts such as IC. If the surfaceroughness Ra is less than 0.6 μm, the surface gloss tends to be high,whereby the machine will malfunction due to reflection on theelectroconductive sheet surface at the image inspection, and if itexceeds 4.0 μm, the surface of the electroconductive sheet tends to betoo rough, and the appearance of the sheet tends to be poor, and thesheet is thereby not suitable as an electroconductive sheet for acarrier tape. Here, the surface roughness Ra is a centerline surfaceroughness in accordance with JIS-B-0651.

[0018] As a substrate layer, preferred is one comprising anacrylonitrile-butadiene-styrene copolymer type resin and/or apolystyrene type resin, one comprising a polyethylene terephthalate typeresin and a polycarbonate type resin, or one comprising an imidatedcopolymer having an aromatic vinyl monomer residue and an unsaturateddicarboxylic acid imide derivative residue. Another component may beincorporated into the substrate layer within a range of not impairingthe purpose of the present invention.

[0019] An electroconductive sheet comprising a substrate layer of athermoplastic resin comprising an acrylonitrile-butadiene-styrenecopolymer type resin and/or a polystyrene type resin and havinglaminated on at least one side of the substrate layer, anelectroconductive resin composition comprising a polycarbonate typeresin and from 5 to 50 wt % of carbon black, is one of preferredconstitutions of the electroconductive sheet.

[0020] The acrylonitrile-butadiene-styrene copolymer type resin to beused in the present invention is one composed mainly of a copolymerconsisting essentially of three components of acrylonitrile, butadieneand styrene, and a commercially available product may be used. Forexample, a copolymer obtained by block or graft polymerization of atleast one monomer selected from an aromatic vinyl monomer and a vinylcyanide monomer to a diene type rubber, or a blended product with saidcopolymer, may be mentioned. Said diene type rubber is a polymerobtained by polymerizing butadiene as a component, and examples of whichinclude polybutadiene, polyisoprene, an acrylonitrile-butadienecopolymer and a styrene-butadiene copolymer. The aromatic vinyl monomermay, for example, be styrene, α-methylstyrene or an alkyl-substitutedstyrene. The vinyl cyanide monomer may, for example, be acrylonitrile,methacrylonitrile or a halogen-substituted acrylonitrile. Specificexamples of the copolymer and the blended product with said copolymerinclude an acrylonitrile-butadiene-styrene terpolymer and one obtainedby polymer-alloying a polybutadiene to an acrylonitrile-styrenebipolymer. Further, an acrylonitrile-styrene bipolymer containing norubber component is also included.

[0021] The polystyrene type resin is a polymer obtained by polymerizingstyrene as a component, and examples of which include one composedmainly of a polystyrene resin for general use or an impact resistantpolystyrene resin, or a mixture thereof.

[0022] In a case where the substrate layer for the electroconductivesheet is made of at least one thermoplastic resin selected from thegroup consisting of an acrylonitrile-butadiene-styrene copolymer typeresin and a polystyrene type resin, a polycarbonate type resin mayfurther be incorporated in an amount of from 1 to 50 wt % based on thethermoplastic resin. By incorporating a polycarbonate type resin, themechanical strength will further be improved. The amount of thepolycarbonate type resin is preferably at most 50 wt % so as to obtainan electroconductive sheet at a low cost.

[0023] In a case where a polyethylene terephthalate type resin and apolycarbonate type resin are used for the substrate layer, theproportion of the polyethylene terephthalate type resin is preferablyfrom 35 to 97 wt %, and the proportion of the polycarbonate type resinis preferably from 3 to 65 wt %, based on the total amount of the twocomponents. In such a case, another component may be incorporatedtherein within a range of not impairing the purpose of the presentinvention.

[0024] As the polycarbonate type resin, one used for theelectroconductive resin composition for the surface layer may be used.The resin for the substrate layer may be the same as or different fromone used for the surface layer. Preferably, the polyethyleneterephthalate type resin is from 35 to 97 wt %, and the polycarbonatetype resin is from 3 to 65 wt %, and more preferably, the polyethyleneterephthalate type resin is from 51 to 97 wt %, and the polycarbonatetype resin is from 3 to 49 wt %, based on the total amount of thepolyethylene terephthalate type resin and the polycarbonate type resin.The folding strength and the secondary processability of theelectroconductive sheet will decrease if the compounding ratio of thepolycarbonate type resin is too low or too high. The balance of thestrength and the secondary processability will be excellent within theabove-mentioned ranges.

[0025] The polyethylene terephthalate type resin may be one composedmainly of ethylene glycol and terephthalic acid or a dimethyl esterthereof. Further, one having a part thereof substituted with, diethyleneglycol, 1,4-tetramethylene glycol, 1,4-cyclohexane dimethanol orheptanemethylene glycol in a case of a glycol component, or e.g.isophthalic acid, 1,5-naphthalene dicarboxylic acid or adipic acid in acase of a dicarboxylic acid component, as a copolymerizable monomer, maybe used. Preferred is a polyethylene terephthalate type resin havingfrom 0.1 to 10 mol % of a 1,4-cyclohexane dimethanol component as aglycol component copolymerized, or a polyethylene terephthalate typeresin having from 1 to 10 mol % of an isophthalic acid component as anacidic component copolymerized, from the viewpoint of moldability.

[0026] More preferred is a polyethylene terephthalate type resincomprising a glycol component and from 1 to 10 mol % of a1,4-cyclohexane dimethanol component copolymerized, sincecrystallization proceeds slowly, and the impact strength is high. With acopolymer with a higher molar ratio of the 1,4-cyclohexane dimethanolcomponent, the crystallization proceeds extremely slowly, whereby therewill be problems such as fusion and blocking in extrusion step, dryingstep or recycle step, or physical properties of a molded product tend tobe deteriorated.

[0027] Further, one having an intrinsic viscosity [η] (hereinafterreferred to as IV value) of from 0.6 to 1.0 dl/g is suitably used, asmeasured at 30° C. when the polyethylene terephthalate type resin isdissolved in a mixed solvent of 1,1,4,4-tetrachloroethane with phenol(in a weight ratio of 60:40). If it is less than 0.6, theelectroconductive sheet or the molded product tends to have insufficientmechanical strength and is likely to break, and if it exceeds 1.0 dl/g,the melt viscosity tends to be high, and extrudability tends to be poor,whereby the productivity will decrease. As the polyethyleneterephthalate type resin, a commercially available product may be used.

[0028] For the substrate layer, an imidated copolymer having an aromaticvinyl monomer residue and an unsaturated dicarboxylic acid imidederivative residue may be used. In such a case, it is preferred that thesubstrate layer further contains an acrylonitrile-butadiene-styrenecopolymer type resin in addition to the imidated copolymer.

[0029] The imidated copolymer is a copolymer having an aromatic vinylmonomer residue and an unsaturated dicarboxylic acid imide derivativeresidue, and one further having an unsaturated dicarboxylic anhydrideresidue may also be used. It may further contain a rubber-like polymer.With respect to the amount of each component, the rubber-like polymer isfrom 0 to 40 wt %, the aromatic vinyl monomer residue is from 30 to 70wt %, the unsaturated dicarboxylic acid imide derivative residue is from20 to 60 wt %, and the unsaturated dicarboxylic anhydride residue isfrom 0 to 15 wt %. Further, a copolymerizable vinyl residue may be usedin an amount of from 0 to 40 wt %. As the imidated copolymer, acommercially available product may be used, such as “Malecca” tradename, sold by Denki Kagaku Kogyo K.K.

[0030] The acrylonitrile-butadiene-styrene copolymer type resin to beused in such a case is not particularly limited, and a commerciallyavailable product may be used. Particularly preferred is anacrylonitrile-butadiene-styrene copolymer type resin comprising from 5to 93 wt % of a graft copolymer obtained by copolymerizing from 5 to 80parts by weight of a rubber-like polymer with from 20 to 95 parts byweight of a monomer mixture comprising from 60 to 90 wt % of an aromaticvinyl monomer, from 10 to 40 wt % of a vinyl cyanide monomer and from 0to 40 wt % of a vinyl monomer copolymerizable with the above monomers,and a resin composition comprising from 0 to 80 wt % of a vinylcopolymer comprising from 60 to 90 wt % of an aromatic vinyl monomerresidue, from 10 to 40 wt % of a vinyl cyanide monomer residue and from0 to 40 wt % of a vinyl monomer residue copolymerizable these with.

[0031] In a case of using an acrylonitrile-butadiene-styrene copolymertype resin together, the imidated copolymer may be used in an amount offrom 5 to 93 wt % based on the total amount of the imidated copolymerand the acrylonitrile-butadiene-styrene copolymer type resin. If it isbeyond this range, heat deterioration is likely to result duringprocessing, or no adequate impact strength tends to be obtained.

[0032] Carbon black may be incorporated into the substrate layer of anycomposition, in a small amount so as not to impair the fluidity. Byincorporating carbon black, the mechanical strength will furtherimprove, and at the same time, such a problem can be overcome that thethickness of the electroconductive sheet tends to be thin when theelectroconductive sheet is formed into a packaging container, wherebye.g. the corner portion of the packaging container may be transparent.

[0033] Carbon black to be incorporated in the substrate layer is notparticularly limited, so long as it can be uniformly dispersed in thesubstrate resin. The amount of carbon black incorporated in theelectroconductive substrate layer, may be within a range of notimpairing the fluidity as mentioned above, and it is preferably from 0.1to 10 wt % based on the thermoplastic resin.

[0034] Into the substrate layer of any composition, another knownthermoplastic resin component such as a polyethylene resin or apolypropylene resin, an olefin type resin such as a copolymer ofethylene or propylene (such as an ethylene-ethylacrylate resin, anethylene-vinyl acetate copolymer resin or an ethylene-α-olefin copolymerresin), or a polyester type resin such as a polyethylene terephthalateresin or a polybutylene terephthalate resin, may be incorporated as amodifier. Further, an additive such as a lubricant, a plasticizer or aprocessing aid may be incorporated as the case requires. Further, forthe substrate layer, the edge or a missed roll of the electroconductivesheet to be generated during production of the electroconductive sheet,or a pulverized product of the molded product, may be recycled in anamount of from 5 to 50 wt %.

[0035] To prepare the electroconductive sheet of the present invention,firstly a part or whole of the starting materials for theelectroconductive resin composition is kneaded and pelletized by meansof a conventional method employing e.g. an extruder, and the obtainedelectroconductive resin composition is sheeted together with athermoplastic resin composition to be an electroconductive substratesheet by a conventional method employing e.g. an extruder.

[0036] With respect to kneading of the electroconductive resincomposition, starting materials may be kneaded all at once or may bestepwisely kneaded in such a manner that, for example, carbon black anda half of the polycarbonate type resin are kneaded, and then the rest ofthe materials are added to the kneaded product, followed by kneading,and it is also possible to add the rest of the materials at the time ofsheeting.

[0037] The electroconductive sheet can be prepared by a known methodemploying e.g. an extruder or a calendering machine. As a method forlaminating the electroconductive resin composition on the substratelayer, the respective layers may be firstly formed into sheets or filmsby a separate extruder and then stepwisely laminated by e.g. athermolaminating method, a dry laminating method or an extrusionlaminating method. Otherwise, the electroconductive resin compositionmay be laminated on the preliminarily formed electroconductive substratesheet, by e.g. extrusion coating. In order to prepare theelectroconductive sheet at a lower cost, it is preferred to obtain alaminated electroconductive sheet all at once by e.g. a multilayercoextrusion method employing a feed block or a multimanifold die.

[0038] The method for bringing the surface roughness Ra to be from 0.6to 4.0 μm is not particularly limited, but a method of incorporating aninorganic filler such as talc, calcium carbonate, mica or isinglass intothe resin, a method of incorporating natural rubber or synthetic rubber,or a method of embossing the surface by an embossing roll, may bementioned. The method of embossing the surface by an embossing roll hassuch advantages that the dynamic properties and fabrication propertiesof the electroconductive sheet will not be impaired, it can be widelyapplied to e.g. a vinyl chloride resin, a polycarbonate resin, apolystyrene resin or a polyethylene terephthalate resin, which is usedas an electroconductive sheet for a carrier tape at the present time,and further, as a cover material, one which is conventionally used canbe utilized as it is.

[0039] The entire thickness of the electroconductive sheet is preferablyfrom 0.1 to 3.0 mm, and the thickness of the electroconductive resincomposition layer is preferably from 2 to 80% of the entire thickness.If the entire thickness is less than 0.1 mm, the strength of thepackaging container to be obtained by forming the electroconductivesheet tends to be inadequate, and if it exceeds 3.0 mm, forming such aspressure forming, vacuum forming or thermo-forming tends to bedifficult. Further, if the thickness of the electroconductive resincomposition layer is less than 2%, the surface resistivity of thepackaging container obtained by forming such an electroconductive sheettends to be so is high that no adequate antistatic effects can beobtained, and it exceeds 80%, the processability in e.g.pressure-forming, vacuum-forming or thermoforming tends to be poor.

[0040] The electroconductive sheet of the present invention is useful asa packaging material for electronic parts such as IC or electronic partsusing IC, and is used for injection-molded trays, vacuum-formed trays,magazines and carrier tapes, and it is particularly suitable for carriertapes.

BEST MODE FOR CARRYING OUT THE INVENTION

[0041] Now, the present invention will be explained in further detailwith reference to Examples. However, it should be understood that thepresent invention is by no means restricted to such specific Examples.

EXAMPLE 1

[0042] As an electroconductive resin composition, an electroconductiveresin compound was obtained by preliminarily kneading a polycarbonatetype resin (Panlight L-1225, manufactured by Teijin Chemicals Ltd.) and12 wt % of KETJENBLACK EC (manufactured by LION-AKZO) based on thepolycarbonate type resin, by means of a φ50 mm vented twin-screwextruder, followed by pelletizing. The electroconductive resin compoundwas laminated on each side of an acrylonitrile-butadiene-styrenecopolymer type resin (Techno ABS YT-346, manufactured by Techno PolymerCo., Ltd.) as a thermoplastic resin for a substrate layer of anelectroconductive sheet, by a feed block method using a φ65 mm extruder(L/D=28), a φ40 mm extruder (L/D=26) and a T-die having a width of 500mm to obtain a three-layer electroconductive sheet having an entirethickness of 300 μm and a thickness of the electroconductive resincomposition layer of 30 μm on each side.

EXAMPLE 2

[0043] As an electroconductive resin composition, an electroconductiveresin compound was obtained by preliminarily kneading a polycarbonatetype resin (Panlight L-1225, manufactured by Teijin Chemicals Ltd.) and20 wt % of Denka Black granules (manufactured by Denki Kagaku KogyoK.K.) based on the polycarbonate type resin, by a φ50 mm ventedtwin-screw extruder, followed by pelletizing. The aboveelectroconductive resin compound was laminated on each side of a mixturecomprising an acrylonitrile-butadiene-styrene copolymer type resin(Techno ABS YT-346, manufactured by Techno Polymer Co., Ltd.) and 5 wt %of a polycarbonate type resin (Panlight L-1225, manufactured by TeijinChemicals Ltd.) added thereto, as a thermoplastic resin for a substratelayer of an electroconductive sheet, in the same manner as in Example 1to obtain a three-layer electroconductive sheet having an entirethickness of 200 μm and a thickness of the electroconductive resincomposition layer of 20 μm on each side.

EXAMPLE 3

[0044] An electroconductive resin compound was obtained in the samemanner as in Example 1. The electroconductive resin compound waslaminated on each side of a resin comprising anacrylonitrile-butadiene-styrene copolymer type resin (Techno ABS YT-346,manufactured by Techno Polymer Co., Ltd.) and 10 wt % of saidelectroconductive resin compound added thereto, as a resin for asubstrate layer of an electroconductive sheet, by using a φ65 mmextruder (L/D=28), two φ40 mm extruders (L/D=26) and a multimanifold diefor three layers of three types, having a width of 650 mm to obtain athree-layer electroconductive sheet having an entire thickness of 500 μmand a thickness of the electroconductive resin composition layer of 40μm on each side.

EXAMPLE 4

[0045] A three-layer electroconductive sheet was obtained in the samemanner as in Example 3 except that a polystyrene type resin (Toyo StyrolE640N, manufactured by Toyo Styrene) was used as the resin for asubstrate layer of an electroconductive sheet.

COMPARATIVE EXAMPLE 1

[0046] A three-layer electroconductive sheet was obtained in the samemanner as in Example 1 except that an electroconductive resin compoundobtained by preliminarily kneading 78 wt % of a polystyrene type resin(Toyo Styrol E640N, manufactured by Toyo Styrene), 10 wt % of a HDPEresin (Hyzex 5000H, manufactured by Mitsui Chemicals, Inc.) and 12 wt %of KETJENBLACK EC (manufactured by LION-AKZO) by a φ50 mm ventedtwin-screw extruder, followed by pelletizing, was used as theelectroconductive resin composition.

COMPARATIVE EXAMPLE 2

[0047] A three-layer electroconductive sheet was obtained in the samemanner as in Example 1 except that an electroconductive resin compoundobtained by preliminarily kneading a polystyrene type resin (Toyo StyrolE640N, manufactured by Toyo Styrene) and 12 wt % of KETJENBLACK EC(manufactured by LION-AKZO) by a φ50 mm vented twin-screw extruder,followed by pelletizing, was used as the electroconductive resincomposition and a polystyrene type resin (Toyo Styrol E640N,manufactured by Toyo Styrene) was used as the resin for a substratelayer of an electroconductive sheet.

[0048] The electroconductive sheets thus prepared were evaluated. Theresults are shown in Table 1. TABLE 1 Tensile properties (flowdirection/width direction) Strength Surface Breaking Strength at yieldTensile Falling resistivity extension at break point modulus off of (Ω)(%) (MPa) (MPa) (MPa) carbon Ex. 1 10⁴ 12/11 42/41 48/49 1760/1718 ⊚ Ex.2 10⁴ 10/9  45/43 52/50 1852/1769 ⊚ Ex. 3 10⁴ 12/12 43/43 50/501812/1750 ⊚ Ex. 4 10⁴ 8/9 40/40 46/45 1720/1680 ⊚ Comp. 10⁴ 99/23 32/2039/38 1469/1453 ◯ Ex. 1 Comp. 10⁴ 96/75 25/20 25/23 1666/1539 X Ex. 2

EXAMPLE 5

[0049] A three-layer electroconductive sheet was obtained in the samemanner as in Example 1 except that embossing was applied on the surfaceof one side of the electroconductive sheet by means of a metal embossingroll having a surface roughness Ra of 3.2 μm.

EXAMPLE 6

[0050] A three-layer electroconductive sheet was obtained in the samemanner as in Example 2 except that embossing was applied on the surfaceof one side of the electroconductive sheet by means of a metal embossingroll having a surface roughness Ra of 0.9 μm.

EXAMPLE 7

[0051] A three-layer electroconductive sheet was obtained in the samemanner as in Example 3 except that embossing was applied on the surfaceof one side of the electroconductive sheet by means of a silicone rubberroll containing sand.

EXAMPLE 8

[0052] A three-layer electroconductive sheet was obtained in the samemanner as in Example 4 except that embossing was applied on the surfaceof one side of the electroconductive sheet by means of a metal embossingroll having a surface roughness Ra of 1.9 μm.

COMPARATIVE EXAMPLE 3

[0053] A three-layer electroconductive sheet was obtained in the samemanner as in Comparative Example 1, except that embossing was applied onthe surface of each side of the electroconductive sheet by means of ametal embossing roll having a surface roughness Ra of 0.3 μm, so thatthe electroconductive sheet had high gloss on the surface of each side.

COMPARATIVE EXAMPLE 4

[0054] A three-layer electroconductive sheet was obtained in the samemanner as in Comparative Example 2 except that embossing was applied onthe surface of one side of the electroconductive sheet by means of ametal embossing roll having a surface roughness Ra of 6.7 μm. However,the surface of the electroconductive sheet had intense irregularities,and the appearance of the sheet was very poor.

[0055] The above electroconductive sheets thus prepared were evaluated.The results are shown in Table 2. TABLE 2 Tensile properties (flowdirection/width direction) Strength Surface Breaking Strength at yieldTensile Falling Surface Image resistivity extension at break pointmodulus off of roughness Surface inspection (Ω) (%) (MPa) (MPa) (MPa)carbon (μm) gloss propriety Ex. 5 10⁴ 12/11 42/41 48/49 1760/1718 ⊚ 3.762 ◯ Ex. 6 10⁴ 10/9  45/43 52/50 1852/1769 ⊚ 0.67 21 ◯ Ex. 7 10⁴ 12/1243/43 50/50 1812/1750 ⊚ 1.09 17 ◯ Ex. 8 10⁴ 8/9 40/40 46/45 1720/1680 ⊚2.11 5 ◯ Comp. 10⁴ 99/23 32/20 39/38 1469/1453 ◯ 0.22 65 X Ex. 3 Comp.10⁴ 96/75 25/20 25/23 1666/1539 X 4.55 1 ◯ Ex. 4

EXAMPLE 9

[0056] A polycarbonate type resin (Panlight L-1225, manufactured byTeijin Chemicals Ltd.), and 12 wt % of carbon black (KETJENBLACK EC,manufactured by LION-AKZO) and 5 wt % of a graft resin (Modiper A-4400,manufactured by NOF Corporation, main chain: 70 wt %/side chain: 30 wt%), based on the polycarbonate type resin, were preliminarily kneaded bymeans of a φ50 mm vented twin-screw extruder, followed by pelletizing,to obtain a resin composition.

[0057] Said resin composition was sheeted by means of a φ65 mm extruder(L/D=28) and a T-die having a width of 500 mm to obtain anelectroconductive sheet having an entire thickness of 300 μm.

EXAMPLE 10

[0058] A polycarbonate type resin (Panlight L-1225, manufactured byTeijin Chemicals Ltd.) and 12 wt % of carbon black (KETJENBLACK EC,manufactured by LION-AKZO) based on the polycarbonate type resin, werepreliminarily kneaded by means of a φ50 mm vented twin-screw extruder,followed by pelletizing, to obtain a resin composition.

[0059] Said resin composition was sheeted by means of a φ65 mm extruder(L/D=28) and a T-die having a width of 500 mm to obtain anelectroconductive sheet having an entire thickness of 300 μm.

EXAMPLE 11

[0060] Using the same resin composition as in Example 9 as a surfacelayer, and an acrylonitrile-butadiene-styrene copolymer type resin(Techno ABS YT-346, manufactured by Techno Polymer Co., Ltd.) as a resinfor a substrate layer, the surface layer was laminated on each side ofthe substrate layer by means of a feed block method using a φ65 mmextruder (L/D=28), a φ40 mm extruder (L/D=26) and a T-die having a widthof 500 mm to obtain a three-layer electroconductive sheet having anentire thickness of 300 μm and a thickness of the resin compositionlayer of 30 μm on each side.

EXAMPLE 12

[0061] A polycarbonate type resin (Panlight L-1225, manufactured byTeijin Chemicals Ltd.), and 20 wt % of acetylene black (Denka Blackgranules, manufactured by Denki Kagaku Kogyo K.K.) as carbon black and10 wt % of a graft resin (Modiper A-4400, manufactured by NOFCorporation), based on the polycarbonate type resin, were preliminarilykneaded by a φ50 mm vented twin-screw extruder, followed by pelletizing,to obtain a resin composition. The above resin composition was laminatedon each side of a mixture comprising an acrylonitrile-butadiene-styrenecopolymer type resin (Techno ABS YT-346, manufactured by Techno PolymerCo., Ltd.) and 5 wt % of a polycarbonate type resin (Panlight L-1225,manufactured by Teijin Chemicals Ltd.) added thereto, as a resin for asubstrate layer, by means of a φ65 mm extruder (L/D=28), two φ40 mmextruders (L/D=26) and a multimanifold die for three layers of threetypes having a width of 650 mm, to obtain a three-layerelectroconductive sheet having an entire thickness of 500 μm and athickness of the surface layer of the resin composition of 40 μm on eachside.

[0062] The above electroconductive sheets thus prepared were evaluated.The results are shown in Table 3. TABLE 3 Tensile properties Fall- Sur-(flow direction/width direction) ing face Break- Strength Dupont offresis- ing ex- Strength at yield Tensile impact of tivity tension atbreak point modulus strength car- (Ω) (%) (MPa) (MPa) (MPa) (J) bon Ex.9 10⁴ 8/7 52/50 52/50 2035/2087 0.95 ⊚ Ex. 10 10⁴ 10/12 54/53 59/582200/2295 0.75 ⊚ Ex. 11 10⁴ 11/10 41/39 47/48 1710/1680 0.65 ⊚ Ex. 1210⁴ 9/8 44/42 50/48 1780/1730 0.68 ⊚

[0063] Examples 9 and 10 are different from the viewpoint that a graftresin was used in Example 9, and it is evident that the Dupont impactstrength increased by incorporation of the graft resin. Further, asevident from Examples 11 and 12, not only a monolayer electroconductivesheet but also a multilayer electroconductive sheet can be prepared byusing the resin composition of the present invention.

EXAMPLE 13

[0064] As a material for a substrate layer, one obtained by blending apolyethylene terephthalate type resin (PET9921, manufactured by Eastman,IV value: 0.80) and a polycarbonate type resin (Panlight L-1250L,manufactured by Teijin Chemicals Ltd.) in a ratio as identified in Table4, followed by stirring for mixing, was used. As a material for asurface layer, a resin comprising 100 parts by weight of a polycarbonatetype resin (Panlight L-1225L, manufactured by Teijin Chemicals Ltd.) and20 parts by weight of carbon black (Denka Black granules, manufacturedby Denki Kagaku Kogyo K.K.) dispersed therein, was used. Each materialwas dried by a dehumidifier. Then, the material for a surface layer andthe material for a substrate layer were simultaneously extruded by a 40mm single-screw extruder and by a 65 mm single-screw extruder,respectively, at an extrusion temperature of from 260 to 300° C., andthe respective molten resins were laminated by means of a feed block forthree layers of two types (thickness slit ratio=1:8:1), extruded by aT-die having a width of 650 mm, and sheeted by a quenching roll toprepare a three-layer electroconductive sheet having a thickness of 0.30mm and a thickness ratio of 1:8:1 (surface layer:substrate layer:surfacelayer).

EXAMPLES 14 AND 15 AND COMPARATIVE EXMAPLES 5 TO 7

[0065] A three-layer electroconductive sheet was prepared in the samemanner as in Example 13 except that the composition was as identified inTable 4.

COMPARATIVE EXMAPLES 8

[0066] Using the same electroconductive resin for a surface layer as inExample 13, the resin was extruded by a φ65 mm single-screw extruder atan extrusion temperature of from 260 to 300° C. to prepare a monolayerelectroconductive sheet.

EXAMPLES 16 AND 17 AND COMPARATIVE EXMAPLES 9 AND 10

[0067] A three-layer electroconductive sheet was prepared in the samemanner as in Example 14 except that the thickness ratio of the sheet asidentified in Table 4.

[0068] With respect to the electroconductive sheets obtained in Examplesand Comparative Examples, the surface resistivity, the tensileproperties, falling off of carbon, folding strength and impact strengthwere evaluated. Further, the electroconductive sheets of Examples andComparative Examples were shaped into a carrier tape by a carrier tapeshaping machine to evaluate secondary processability. The results areshown in Table 5. TABLE 4 Examples Comparative Examples 13 14 15 16 17 56 7 8 9 10 Substrate layer PC type resin 60 40 20 40 40  0 100 80 — 4040 PET type resin 40 60 80 60 60 100  0 20 — 60 60 Surface layer PC typeresin 100  100  100  100  100  100 100 100  100 100  100  Thicknessratio of surface layer/substrate 1/8/1 1/8/1 1/8/1 1/18/1 1/6/1 1/8/11/8/1 1/8/1 — 3/1/3 1/100/1 layer/surface layer

[0069] TABLE 5 Examples Comparative Examples 13 14 15 16 17 5 6 7 8 9 10Surface resistivity Ω 2.4 × 3 × 1.9 × 3.2 × 2.3 × 2.8 × 3.1 × 4.1 × 1.9× 2.3 × 5.2 × 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10⁴ 10¹² TensileBreaking extension % 118 136 195 156 89 301 71 75 13 28 169 propertiesStrength at yield point MPa 49 47 46 47 47 46 53 51 59 48 47 Strength atbreak MPa 62 55 49 55 55 47 60 56 55 56 54 Tensile modulus MPa 1566 16281629 1635 1631 1530 1520 1732 1641 1655 1590 Falling off of carbon — ⊚ ⊚⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Folding strength Times 251 384 1083 415 350 3020 21 3815 27 430 Impact strength J 0.7 0.6 0.5 0.7 0.6 1.1 0.5 0.8 0.9 0.8 0.6Secondary processability — ◯ ◯ ◯ ◯ ◯ X Δ ◯ X Δ ◯

EXAMPLE 18

[0070] A polycarbonate type resin (Panlight L-1225, manufactured byTeijin Chemicals Ltd.) and 12 wt % of carbon black (KETJENBLACK EC,manufactured by LION-AKZO) based on the polycarbonate type resin werepreliminarily kneaded by a φ50 mm vented twin-screw extruder, followedby pelletizing, to obtain an electroconductive resin compound. Theelectroconductive resin compound was laminated on each side of animidated copolymer (Denka Malecca K-400, manufactured by Denki KagakuKogyo K.K.) as a resin for a substrate layer, by means of a feed blockmethod using a φ65 mm extruder (L/D=28), a φ40 mm extruder (L/D=26) anda T-die having a width of 500 mm, to obtain a three-layerelectroconductive sheet having an entire thickness of 300 μm and athickness of the surface layer of 30 μm on each side.

EXAMPLE 19

[0071] A polycarbonate type resin (Panlight L-1225, manufactured byTeijin Chemicals Ltd.) and 20 wt % of carbon black (Denka Blackgranules, manufactured by Denki Kagaku Kogyo K.K.) based on thepolycarbonate type resin were preliminarily kneaded by a φ50 mm ventedtwin-screw extruder, followed by pelletizing, to obtain anelectroconductive resin compound. Using an imidated copolymer (DenkaMalecca K-510, manufactured by Denki Kagaku Kogyo K.K.) as a resin for asubstrate layer, a three-layer electroconductive sheet having an entirethickness of 200 μm and a thickness of the surface layer of 20 μm oneach side was prepared in the same manner as in Example 18.

EXAMPLE 20

[0072] An electroconductive compound was obtained in the same manner asin Example 18. The electroconductive compound was laminated on each sideof a resin comprising an imidated copolymer (Denka Malecca K-400,manufactured by Denki Kagaku Kogyo K.K.) and 10 wt % of the aboveelectroconductive compound added thereto, as a resin for a substratelayer, by using of a φ65 mm extruder (L/D=28), two φ40 mm extruders(L/D=26) and a multimanifold die for three layers of three types havinga width of 650 mm, to obtain a three-layer electroconductive sheethaving an entire thickness of 500 μm and a thickness of the surfacelayer of 40 μm on each side.

EXAMPLE 21

[0073] A three-layer electroconductive sheet was obtained in the samemanner as in Example 18 except that an imidated copolymer (Denka MaleccaK-610, manufactured by Denki Kagaku Kogyo K.K.) was used as the resinfor a substrate layer.

COMPARATIVE EXAMPLE 11

[0074] A three-layer electroconductive sheet was obtained in the samemanner as in Example 18 except that an electroconductive resin compoundobtained by preliminarily kneading a polystyrene resin (Toyo StyrolE640N, manufactured by Toyo Styrene), and 10 wt % of a polyethyleneresin (Hyzex 5000H, manufactured by Mitsui Chemicals, Inc.) and 12 wt %of carbon black (KETJENBLACK EC, manufactured by LION-AKZO), based onthe polystyrene resin, by a φ50 mm vented twin-screw extruder, followedby pelletizing, was used as the electroconductive resin composition, andan acrylonitrile-butadiene-styrene copolymer type resin (Techno ABSYT-346, manufactured by Techno Polymer Co., Ltd.) was used as the resinfor a substrate layer.

COMPARATIVE EXAMPLE 12

[0075] A three-layer electroconductive sheet was obtained in the samemanner as in Example 18 except that an electroconductive resin compoundobtained by preliminarily kneading a polystyrene resin (Toyo StyrolE640N, manufactured by Toyo Styrene) and 12 wt % of carbon black(KETJENBLACK EC, manufactured by LION-AKZO) based on the polystyreneresin, by a φ50 mm vented twin-screw extruder, followed by pelletizing,was used as the electroconductive resin composition, and a polystyreneresin (Toyo Styrol E640N, manufactured by Toyo Styrene) was used as theresin for a substrate layer.

[0076] The above electroconductive sheets thus prepared were subjectedto the following evaluations. TABLE 6 Tensile properties (flowdirection/width direction) Strength Surface Breaking Strength at yieldTensile Falling resistivity extension at break point modulus off of (Ω)(%) (MPa) (MPa) (MPa) carbon Ex. 18 10⁴ 28/16 46/43 50/47 1903/1931 ⊚Ex. 19 10⁴ 22/14 41/40 43/42 1755/1647 ⊚ Ex. 20 10⁴ 12/12 49/44 52/501951/1980 ⊚ Ex. 21 10⁴ 17/11 42/38 44/42 1756/1620 ⊚ Comp. 10⁴ 99/5235/32 43/42 1536/1463 ◯ Ex. 11 Comp. 10⁴ 95/89 21/20 20/19 1166/1139 XEx. 12

[0077] The evaluation methods were as follows.

[0078] The physical properties were measured at 23° C. under a humidityof 50% unless otherwise specified. With respect to the folding strengthand the impact strength, the evaluation results were in accordance withstandards as an electroconductive sheet, which is commoner than a moldedproduct.

[0079] Surface Resistivity

[0080] Using a Rolestar MCP tester manufactured by MitsubishiPetrochemical Co., Ltd, the distance between terminals was set to be 10mm, and the resistivity of the electroconductive sheet was measured atten points at even intervals in a width direction in two lines on eachside, i.e. at 40 points in total, whereupon the logarithmic mean valuewas taken as the surface resistivity.

[0081] Tensile Properties

[0082] In accordance with JIS-K-7127, tensile test was carried out bymeans of an Instron type tensile tester at a tension speed of 10 mm/minusing a No. 4 test specimen, and the average of measured values in aflow direction and in a width direction was taken as the evaluationresult.

[0083] Dupont Impact Strength

[0084] Using a Dupont impact tester (manufactured by TOYO SEIKISEISAKU-SHO, LTD.), a bullet was made to fall on the electroconductivesheet to obtain a height at 50% break, and the energy value wascalculated from the weight of the bullet at said height. The calculationwas carried out in accordance with JIS-K-7211.

[0085] Evaluation of Falling Off of Carbon

[0086] The electroconductive sheet in a film form was formed into acarrier tape having a pocket with a size of 19 mm×25 mm, which was fixedon a shaking table. IC of QFP 14 mm×20 mm-64 pin was mounted in thepocket portion and vibrated at a speed of 480 reciprocations per minutewith a stroke of 30 mm in a plane direction for 800,000 times, whereuponthe presence or absence of depositions on the lead portion of IC wasevaluated. The evaluation standards were ⊚: substantially no depositionobserved, ◯: some depositions observed, and X: many depositionsobserved.

[0087] Surface Roughness

[0088] The centerline surface roughness was measured by means of Surfcom120A manufactured by TOKYO SEIMITSU CO., Ltd, in accordance withJIS-B-0651.

[0089] Surface Gloss

[0090] The gloss of the electroconductive sheet was measured at 5 pointson each side by means of a gloss checker IG-301 manufactured by Horiba,Ltd. to obtain the average value on each side, and the lower value wastaken as the gloss.

[0091] Image Inspection Propriety Test

[0092] The electroconductive sheet in a film form was formed into acarrier tape having a pocket with a size of 19 mm×25 mm. IC of QFP 14mm×20 mm-100 pin was mounted in the pocket portion, whereupon thepresence or absence of virtual image at the bottom of the pocket wasconfirmed by a CCD camera of 360,000 pixel. The evaluation standardswere X: virtual image clearly confirmed, Δ: virtual image unclearlyconfirmed, and ◯: no virtual image confirmed.

[0093] Folding Strength

[0094] In accordance with JIS-P-8116, sampling was carried out in a flowdirection of the electroconductive sheet, and evaluation was carried outwith a load of 500 g with a folding speed of 175 reciprocations perminute.

[0095] Secondary Processability

[0096] A carrier tape having a width of 24 mm was prepared from theelectroconductive sheet by means of a carrier tape shaping machine(manufactured by EDG) to evaluate processability. The evaluationstandards were ◯: good, Δ: somewhat poor, and X: poor.

INDUSTRIAL APPLICABILITY

[0097] According to the present invention, an electroconductive sheetfor packaging an electronic part, which substantially reduces stainingof the electronic part due to abrasion of the electroconductive sheetwith the electronic part, and which has adequate mechanical strength toendure packaging and mounting of an electronic part at a high speed, anda packaging container for an electronic part, are provided.

1. An electroconductive sheet comprising a substrate layer of athermoplastic resin comprising an acrylonitrile-butadiene-styrenecopolymer type resin and/or a polystyrene type resin and havinglaminated on at least one side of the substrate layer, a surface layerof an electroconductive resin composition comprising a polycarbonatetype resin and from 5 to 50 wt % of carbon black.
 2. Theelectroconductive sheet according to claim 1, wherein the substratelayer further contains from 1 to 50 wt % of a polycarbonate type resinbased on the thermoplastic resin.
 3. An electroconductive sheetcomprising a substrate layer and having laminated on at least one sideof the substrate layer, a surface layer of an electroconductive resincomposition comprising a polycarbonate type resin, and from 5 to 50 wt %of carbon black and at most 40 wt % of a graft resin of anethylene-glycidylmethacrylate type copolymer with anacrylonitrile-styrene type copolymer, based on the polycarbonate typeresin.
 4. The electroconductive sheet according to claim 3, wherein thesubstrate layer comprises an acrylonitrile-butadiene-styrene copolymertype resin and/or a polystyrene type resin.
 5. An electroconductivesheet comprising a substrate layer comprising a polyethyleneterephthalate type resin and a polycarbonate type resin in suchproportions that based on the total of the two components, thepolyethylene terephthalate type resin is from 35 to 97 wt % and thepolycarbonate type resin is from 3 to 65 wt %, and having on at leastone side of the substrate layer, a surface layer of an electroconductiveresin composition comprising a polycarbonate type resin and from 5 to 50wt % of carbon black, wherein the thickness of the surface layer is from2 to 80% of the entire thickness.
 6. An electroconductive sheetcomprising a substrate layer containing an imidated copolymer having anaromatic vinyl monomer residue and an unsaturated dicarboxylic acidimide derivative residue, and having laminated on at least one side ofthe substrate layer, a surface layer of an electroconductive resincomposition comprising a polycarbonate type resin and from 5 to 50 wt %of carbon black based on the polycarbonate type resin.
 7. Theelectroconductive sheet according to claim 6, wherein the imidatedcopolymer further contains a rubber-like polymer and an unsaturateddicarboxylic anhydride residue.
 8. An electroconductive sheet comprisinga substrate layer comprising an imidated copolymer having from 0 to 40wt % of a rubber-like polymer, from 30 to 70 wt % of an aromatic vinylmonomer residue, from 20 to 60 wt % of an unsaturated dicarboxylic acidimide derivative residue and from 0 to 15 wt % of an unsaturateddicarboxylic anhydride residue, and having laminated on at least oneside of the substrate layer, a surface layer of an electroconductiveresin composition comprising a polycarbonate type resin and from 5 to 50wt % of carbon black based on the polycarbonate type resin.
 9. Theelectroconductive sheet according to claim 8, wherein the imidatedcopolymer further contains a copolymerizable vinyl residue in an amountof more than 0 wt % and not more than 40 wt %.
 10. The electroconductivesheet according to any one of claims 6 to 9, wherein the substrate layerfurther contains an acrylonitrile-butadiene-styrene copolymer typeresin.
 11. The electroconductive sheet according to claim 10, whereinthe amount of the imidated copolymer is form 5 to 93 wt % based on thetotal amount of the imidated copolymer and theacrylonitrile-butadiene-styrene copolymer type resin.
 12. Theelectroconductive sheet according to any one of claims 1 to 11, whereinthe substrate layer contains from 0.1 to 10 wt % of carbon black basedon the total amount of the resin.
 13. The electroconductive sheetaccording to any one of claims 1 to 12, wherein the surface layer has asurface roughness of from 0.6 μm to 4.0 μm.
 14. The electroconductivesheet according to any one of claims 1 to 13, which has a surfaceresistivity of from 10² to 10¹⁰ Ω on the side on which the surface layeris laminated.
 15. The electroconductive sheet according to any one ofclaims 1 to 14, which is produced by coextrusion.
 16. A resincomposition comprising a polycarbonate type resin, and from 5 to 50 wt %of carbon black and at most 40 wt % of a graft resin of anethylene-glycidylmethacrylate type copolymer with anacrylonitrile-styrene type copolymer, based on the polycarbonate typeresin.
 17. A molded product made of the resin composition as defined inclaim
 16. 18. An electroconductive sheet made of the resin compositionas defined in claim
 16. 19. An electroconductive sheet for packaging anelectronic part, which is made of the electroconductive sheet as definedin any one of claims 1 to 15 and
 18. 20. A packaging container for anelectronic part, which is made of the electroconductive sheet forpackaging an electronic part as defined in claim
 19. 21. A carrier tapemade of the electroconductive sheet for packaging an electronic part asdefined in claim 20.